mysql创建表间关系

-- 创建用户表
CREATE TABLE users (
    user_id INT PRIMARY KEY AUTO_INCREMENT,
    username VARCHAR(50) NOT NULL
);

-- 创建用户详情表
CREATE TABLE user_details (
    detail_id INT PRIMARY KEY AUTO_INCREMENT,
    user_id INT UNIQUE NOT NULL,
    email VARCHAR(100),
    FOREIGN KEY (user_id) REFERENCES users(user_id)
);

-- 创建部门表
CREATE TABLE departments (
    dept_id INT PRIMARY KEY AUTO_INCREMENT,
    dept_name VARCHAR(50) NOT NULL
);

-- 创建员工表
CREATE TABLE employees (
    emp_id INT PRIMARY KEY AUTO_INCREMENT,
    emp_name VARCHAR(50) NOT NULL,
    dept_id INT,
    FOREIGN KEY (dept_id) REFERENCES departments(dept_id)
);

-- 创建学生表
CREATE TABLE students (
    student_id INT PRIMARY KEY AUTO_INCREMENT,
    student_name VARCHAR(50) NOT NULL
);

-- 创建课程表
CREATE TABLE courses (
    course_id INT PRIMARY KEY AUTO_INCREMENT,
    course_name VARCHAR(50) NOT NULL
);

-- 创建中间表
CREATE TABLE student_courses (
    student_id INT,
    course_id INT,
    PRIMARY KEY (student_id, course_id),
    FOREIGN KEY (student_id) REFERENCES students(student_id),
    FOREIGN KEY (course_id) REFERENCES courses(course_id)
);

SET FOREIGN_KEY_CHECKS=0;
-- 插入数据
SET FOREIGN_KEY_CHECKS=1;